Mosjøen (Southern Sami: Mussere) listen is a town, a former town municipality, and a former privileged staple place in the Municipality of Vefsn in the southern part of the County of Northland, Norway. Established in 1875, Mosjøen is the oldest town in the Helgeland region, and only Bodø is older within Nordland. The 6.41-square-kilometre (1,580-acre) village has a population (2013) of 9,665 giving the village a population density of 1,508 inhabitants per square kilometre (3,910 /sq mi).
Together with Mo i Rana and Narvik, Mosjøen is one of the industrial towns in Nordland. The Mosjøen Aluminum Plant, owned by Alcoa, is among the biggest in Europe and traditionally the town's cornerstone enterprise. Additionally, the town has a business sector that includes trade, crafts, banking, transportation, and tourism. The town attracts customers from the whole region.
Mosjøen is a centre of communications in Helgeland. From Mosjøen, there are 71 kilometres (44 miles) to Sandnessjøen in the west, 87 kilometres (54 miles) to Mo i Rana in the north, and 160 kilometres (99 miles) to Brønnøysund in the south. Furthermore, the road distance is 318 km (198 miles) to Bodø and 393 km (244 miles) to Trondheim. The E6 goes through the town. There are daily departures from the Mosjøen Bus Central, from the Mosjøen Railway Station on the Nordland Line, and from Mosjøen Airport south of the town. There are both public and private quays in Mosjøen. The town's harbour is among the largest in Northern Norway.
In the aspect of basic education, Mosjøen has both local and regional functions. The Mosjøen High School receives students from the town and rural municipalities surrounding it. The Vefsn Folk High School is located in Mosjøen. The town has a department of the Open University. Many bigger events for children and youths take place in Mosjøen, among others the Toppen International Summer Music School and the Kippermoen Cup.
Mosjøen is known for the famous Sjøgata with its 19th century wooden houses and piers. Other sightseeing spots are the Dolstad Church, the Town Park, and the aluminum plant.